Comment out calls to httptest.Server.Close() to work around

https://github.com/golang/go/issues/12262 . See #19254 for
more details. This change should be reverted when we upgrade
to Go 1.6.

pkg/genericapiserver/genericapiserver_test.go

@@ -114,6 +114,7 @@ func TestInstallAPIGroups(t *testing.T) {
 	}
 	s.InstallAPIGroups(apiGroupsInfo)
 
+	// TODO: Close() this server when fix #19254
 	server := httptest.NewServer(s.HandlerContainer.ServeMux)
 	validPaths := []string{
 		// "/api"